Variations In Soil Infiltration And Soil Resistance Under Different Vegetation Restoration Types In Benggang Area

Benggang is the most harmful soil erosion disaster in the red soil area of Southern China,which poses a huge threat to the local ecological security,and also severely restricts and hinders the development of the local regional economy.The investigation and research of Benggang was carried out in the 1940s,and dozens of governance models have been formed over more than half a century.On the basis of previous research,the management of Benggang can be summarized into three governance modes:type of ecological protection,type of industrial economical,type of perfect restoration.After restoration,the vegetation restoration of Benggang has been greatly improved,and soil quality has been improved.At present,soil quality evaluation is mainly carried out in the area after vegetation restoration by constructing soil quality indicators.However,the changes of various indicators and anti-resistance ability after vegetation restoration need to be further studied.This study was performed in the Jingouxing small watershed,which is located in Ganxian county,Jiangxi Province,China.Four typical vegetation restoration types of topsoil were selected as the experimental materials,and unrepaired Benggang as the control,a total of five test plots.Field investigation and experiment,determination of physical and chemical properties and soil near-surface characteristics,the measurement of the in-situ infiltration and soil detachment were carried out in the experimental area.Based on the distribution of soil physicochemical properties and near-surface characteristic parameters,combined with the change characteristics of soil infiltration and soil resistance,the change mechanism and main influencing factors of soil infiltration and soil resistance of different vegetation restoration types in Benggang area were comprehensively analyzed.(1)Significant differences in the basic physicochemical properties and soil near-surface characteristics under the vegetation restoration in Benggang area,and during the process of vegetation restoration,soil physicochemical properties and soil near-surface characteristics interacted with each other.The physical structure of the soil in the Benggang area is poor.The particle composition is mostly silt,followed by clay content and sand content,and the soil texture is silty loam.After the vegetation restoration,the soil bulk density is reduced,and the organic matter content and soil cohesion are significantly increased.Both clay content and soil organic matter content can affect the state of soil consolidated.Especially soil organic matter content,which can improve the bonding between particles.The higher the content,the stronger the soil consolidation stability,the stronger the quality and the anti-resistance ability.For the soil near-surface characteristics,the biological crust thickness on the soil surface significantly increased during the vegetation restoration process,and the root characteristics also increased in different degrees.(2)The parameters of soil infiltration properties under different vegetation restoration types in the Benggang area are characterized as the eroded land>the artificial grassland>the artificial scrubland>the artificial orchard>the artificial forest.Based on the stepwise regression and the path analysis,the soil physicochemical properties and soil near-surface characteristics under different vegetation restoration types in Benggang area are analyzed.Sand content,organic matter content,biological crust thickness and root length density are the main factors affecting soil infiltration performance.In terms of the initial infiltration rate,the steady infiltration rate,and hydraulic conductivity,the smallest data set composed of them can explain 95%,96%and 96%of the physicochemical properties and soil near-surface characteristics,respectively.The standardized path coefficients are 0.998,0.998 and 0.997,respectively.There,it can be used as a reasonable index to evaluate the effect of vegetation restoration on soil infiltration performance.(3)Significant differences are found in the soil resistance under different vegetation restoration types,among which,the soil near-surface characteristics significantly enhanced the soil resistance.Soil detachment rate is an important indicator of soil corrosion resistance,and its sample plot changes are characterized by the eroded land>the artificial grassland>the artificial scrubland>the artificial orchard>the artificial forest.Soil rill erodibility decreased significantly with vegetation restoration,but soil critical shear stress increased.Based on the WEEP(Water Erosion Prediction Project)model,the sand content,soil organic matter content and root length density can be used to estimate the changes in soil rill erodibility(NSE=0.814);soil cohesion and biological crust thickness can be used to represent soil critical shear stress(NSE=0.632).The soil detachment is characterized by the sand content,soil organic matter content,soil cohesion,biological crust thickness and root length density.Further regression simulation analysis is carried out through the equation,and the prediction model of the soil detachment rate during the vegetation restoration process in the Benggang area is obtained.The determination coefficient(R~2)and Nash-Sutcliffe coefficient(NSE)of the prediction equation are 0.812 and 0.827,respectively.The results can be used to estimate the variations of soil detachment rate under different vegetation restoration types in the Benggang area of Southern China.